Chilli Colour Sorting & Grading

Optical Colour Sorting Technology

Gaman Impex's colour sorting operation uses high-resolution CCD (charge-coupled device) camera systems that capture multi-spectral images of individual chilli pods moving at high speed on the sorting conveyor. The system processes images in real time, comparing each pod against pre-programmed acceptance criteria for colour, shape, and surface texture. Pods that fall outside acceptance parameters are ejected by precisely timed air jets, achieving detection and removal at speeds that manual sorting cannot match.

What Gets Sorted Out

• Discoloured pods — Yellowed, bleached, or over-dried chillies that reduce visual grade and ASTA colour value
• Mouldy pods — Surface mould visible to camera detection; mouldy pods are a primary source of aflatoxin contamination
• Immature pods — Under-ripe pods with different spectral signature from mature red chillies
• Damaged and shrivelled pods — Physically damaged, insect-bored, or heavily shrivelled pods that affect grade uniformity
• Foreign matter — Any remaining stones, seeds, or debris that passed the cleaning stages

Gravity Separation

Following optical sorting, chilli lots also pass through a gravity separator — a vibratory table that uses specific gravity differences to separate lighter, hollow, or damaged pods from heavier, well-filled pods. This stage is particularly important for separating aflatoxin-prone hollow pods, which are significantly lighter than healthy filled pods. Gravity separation adds a critical second dimension to quality separation that colour sorting alone cannot provide.

ASTA Colour Value — What Buyers Require

ASTA (American Spice Trade Association) colour value is the international standard for measuring colour strength in dry red chillies and paprika. Expressed as ASTA units, higher values indicate more intense red colour — which translates directly to higher value in global spice markets. Most export buyers specify minimum ASTA values per variety:

• Teja S17: ASTA 40–80 (pungency-focused variety, lower colour)
• S4 Guntur Sannam: ASTA 60–100
• Byadgi: ASTA 150–200+ (colour extraction grade)
• 334 Chilli: ASTA 80–120

Gaman Impex tests ASTA colour values on post-sorting samples sent to NABL-accredited laboratories. ASTA certificates are provided as part of the Certificate of Analysis (COA) documentation accompanying each shipment.

Aflatoxin Risk Reduction Through Sorting

Aflatoxin contamination in dry red chillies is primarily associated with mouldy, damaged, or hollow pods — exactly the pods that optical colour sorting and gravity separation target. While sorting is not a substitute for NABL lab testing for aflatoxin levels, it significantly reduces the risk of aflatoxin-positive lots by physically removing the primary contamination vectors. All post-sorting lots are still tested for aflatoxin B1 at NABL-accredited labs before shipment confirmation.